Leonardo Ribeiro | UNIMONTES universidade estadual de Montes Claros (original) (raw)

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Papers by Leonardo Ribeiro

Page 1. SIMÕES, MOM; et. al. UNIMONTES CIENTÍFICA. Montes Claros, v.5, n.1, jan./jun. 2003 Estudo... more Page 1. SIMÕES, MOM; et. al. UNIMONTES CIENTÍFICA. Montes Claros, v.5, n.1, jan./jun. 2003 Estudo anatômico do Mesófilo Foliar de Albizia Spp (Leguminosae / Mimosoidea) Anatomical study of Leaf Mesophyll of Albizia Spp (Leguminosae/ Mimosoidea) ...

Plant Physiology and Biochemistry, Sep 1, 2017

Industrial Crops and Products, Mar 1, 2022

Seed Science and Technology, Dec 15, 2015

Forest Ecology and Management

Microscopy and Microanalysis, 2022

The objective of this work was to characterize the ontogenesis of Protium spruceanum secretory du... more The objective of this work was to characterize the ontogenesis of Protium spruceanum secretory ducts, to evaluate the effects of seasonality on that process, and to characterize the chemical nature of the resin. Morphometric, anatomical, micromorphometric, histochemical, and ultrastructural evaluations of shoot apexes and chemical analyses of the resin were performed. The ducts of schizolysigenous origin are distributed in the primary and secondary phloem. The subsecretory tissue is meristematic and can restore the secretory epithelium. Secretory epithelial cells have wall thickening resembling that of the Casparian strip that regulates secretion reflux. The main resin compounds are pentacyclic triterpenoids, α- and β-amyrins, and α- and β-amyrenones, which are reported here for the first time for this species. The presence of electron-dense and electron-opaque structures, in the secretory epithelial cells, are compatible with the triterpenes and mucilage identified in the resin. Ri...

Forest Ecology and Management, 2022

Scientia Horticulturae, 2022

Plant Cell, Tissue and Organ Culture (PCTOC), 2020

Trees, 2021

Hydration cycles promote embryo physiological changes, favoring overcoming dormancy in Butia capi... more Hydration cycles promote embryo physiological changes, favoring overcoming dormancy in Butia capitata seed banks. Dormant seeds can spend many years in soil seed banks while subject to successive hydration and dehydration cycles (HC). Our knowledge concerning the effects of HC on seed survival and on overcoming dormancy is still limited, especially among tropical species. We sought to evaluate structural and physiological aspects of the diaspores (pyrenes: seeds enclosed by the endocarp) of the neotropical palm Butia capitata submitted to HC (in association with thermal regimes) under laboratory conditions and in a simulated soil seed bank. Biometric, anatomical, histochemical, biomechanical (the resistance of restrictive structures to embryo growth), and physiological (viability, the potential for in vitro embryo elongation, germination, and endo-β-mannanase activity) evaluations were performed. HC, in association with thermal regime variations, positively affect the growth potential of the embryos, which is related to an increase in their water absorption capacity, increased cell division, embryo expansion, and endosperm reserve mobilization. Those changes result in a gradual decrease in dormancy intensity, allowing a gradual exit from the soil seed bank through germination. Diaspores of B. capitata present morphophysiological dormancy of a particular type that is characterized by restricted embryo growth inside the seed before germination, low levels of endosperm reserve mobilization, and the gradual overcoming of dormancy over several years. The ability to form soil seed banks is an important adaptive strategy when faced with a seasonal environment with irregular rainfall in which the species occurs.

Plant Physiology and Biochemistry, 2020

Microscopy and Microanalysis, 2020

Mauritia flexuosa palms inhabit wetland environments in the dry, seasonal Brazilian savanna (Cerr... more Mauritia flexuosa palms inhabit wetland environments in the dry, seasonal Brazilian savanna (Cerrado) and produce mucilaginous secretions in the stem and petiole that have a medicinal value. The present study sought to characterize the chemical natures of those secretions and to describe the anatomical structures involved in their synthesis. Chemical analyzes of the secretions, anatomical, histochemical analyses, and electron microscopy studies were performed on the roots, stipes, petioles, and leaf blades. Stipe and petiole secretions are similar, and rich in cell wall polysaccharides and pectic compounds such as rhamnose, arabinose, xylose, mannose, galactose, and glucose, which are hydrophilic largely due to their hydroxyl and carboxylate groups. Mucilaginous secretions accumulate in the lumens of vessel elements and sclerenchyma fibers of the root, stipe, petiole, and foliar veins; their synthesis involves cell wall loosening and the activities of dictyosomes. The outer faces of...